Vehicle Communication System

ABSTRACT

A communication system for facilitating control over a function of a vehicle ( 102 ) comprises a base station ( 104 ) positioned in the vehicle ( 102 ) and a mobile communication unit ( 122 ). The base station ( 104 ) comprises a first transmitter for transmitting a signal to the mobile communication unit ( 122 ) and a first receiver for receiving a signal from the mobile communication unit ( 122 ). The base station ( 104 ) is further configured to cause the mobile communication unit ( 122 ) to operate in accordance with a limited-response duty cycle.

TECHNICAL FIELD

The present invention relates to a vehicle communication system forfacilitating control over vehicle functions. The present inventionrelates more particularly, but not exclusively, to systems and methodsfor facilitating control over vehicle functions based, at least in part,on position of a mobile communication unit. Aspects of the inventionrelate to a system, to a method and to a vehicle.

BACKGROUND OF THE INVENTION

In today's world, many vehicles are equipped with systems forfacilitating remotely controlled vehicle functions such as passive entryand passive starting (i.e., PEPS) of a host vehicle. When a vehicle isequipped with a PEPS system, a user carries a mobile communication unitwhich can communicate with a base station located in the vehicle. Toconserve use of energy stored in its internal battery, system componentsmay remain in a low power state until an initiating trigger (forexample, manipulation of a vehicle door handle) awakens one or moreother system components. For example, upon sensing that a door handlehas been manipulated, the base station may emit a relatively powerfulLow Frequency (LF) electromagnetic field, causing a mobile communicationunit that is sufficiently close to the base station to awaken. Once themobile communication unit is awake, it may use Radio Frequency (RF)transmissions to dispatch a response signal, which may be validated bythe base station. If the base station recognizes and approves theidentity of the mobile communication unit, (i.e., the base stationauthenticates the mobile communication unit), the base station mayfacilitate the performance of a predefined vehicle function, such asactuating a door lock mechanism, causing the door to become unlocked.

Because the amount of energy required by the base station to generate aLF field is significant, many such systems employ a sleep mode andawaken only upon the occurrence of a trigger event. Unfortunately, theuse of an initiating trigger causes the sequence of authenticating themobile communication unit to be performed within an extremely shortamount of time so as to avoid the nuisance of experiencing a delay inthe vehicle response. Fast-release motors may be employed to perform theactuation functions such as unlocking a door.

Means may be provided for monitoring movements of the mobilecommunication unit such that, after a period of time in which the mobilecommunication unit has remained stationary and has not been otherwiseactivated, the mobile communication unit would be caused to enter thesleep mode. Unfortunately, when the mobile communication unit is in thevehicle, physical movements of the vehicle may be misinterpreted asmovements of the mobile communication unit even though the mobilecommunication unit may be stationary with respect to the vehicle. Underthose circumstances, the misinterpreted vehicle movements may preventthe mobile communication unit from entering the sleep mode whenever thevehicle is moving. The present invention attempts to address orameliorate at least some of the above problems associated with vehiclecommunication systems.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a communication system forfacilitating control over a function of a vehicle comprises a basestation positioned in the vehicle and a mobile communication unit. Thebase station comprises a first transmitter for transmitting a signal tothe mobile communication unit and a first receiver for receiving asignal from the mobile communication unit. The base station is furtherconfigured to cause the mobile communication unit to operate inaccordance with a limited-response duty cycle. Thus, the vehiclecommunication system provides an energy-saving in-vehicle mode withoutcompromising relatively continuous communication between the basestation and the mobile communication unit.

The base station may be configured for determining a location of themobile communication unit relative to the vehicle and may be configuredto cause the mobile communication unit to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit is located within the vehicle. Alternatively,the base station may be configured to cause the mobile communicationunit to operate in accordance with the limited-response duty cycle inresponse to a determination that the mobile communication unit issubstantially stationary relative to the vehicle. Still further, thebase station may be configured to cause the mobile communication unit tooperate in accordance with the limited-response duty cycle in responseto a determination that the mobile communication unit is located withinthe vehicle and the mobile communication unit is substantiallystationary relative to the vehicle.

In another aspect, the present invention provides a communication systemfor facilitating control over a function of a vehicle comprising a basestation positioned in the vehicle and a mobile communication unit,wherein the base station is configured to cause the mobile communicationunit to resume operating in accordance with a high-response duty cyclein response to an occurrence of a predetermined trigger event. Thepredetermined trigger event may correspond to an opening of a door ofthe vehicle. In addition, the predetermined trigger event may correspondto a closing of a door of the vehicle. Still further, the predeterminedtrigger event may correspond to a request to start the engine of thevehicle.

In a further aspect, the invention provides a communication system forfacilitating control over a function of a vehicle comprising a basestation positioned in the vehicle and a mobile communication unit. Thebase station comprises a first transmitter for transmitting a pollingsignal and a first receiver for receiving an authentication signal fromthe mobile communication unit in response to the polling signal. Thebase station is further configured to cause the mobile communicationunit to operate in accordance with a limited-response duty cycle thatcomprises a period of inactivity, during which the mobile communicationunit is unable to receive a transmission, and a period of activity,during which the mobile communication unit is capable of receiving atransmission. The period of inactivity may be longer in time than theperiod of activity. The period of inactivity may extend forapproximately two seconds before a subsequent period of activity, andthe period of activity may extend for approximately three microsecondsbefore a subsequent period of inactivity.

The high-response duty cycle may comprise a period of activity, duringwhich the mobile communication unit is capable of receiving atransmission, and the period of activity may occur without substantialinterruption by a period of inactivity. The period of inactivity may notbe longer in duration than one second. Alternatively, the period ofinactivity may not be longer in duration than one half of one second.

In a further aspect, the base station may be configured for determininga location of the mobile communication unit relative to the vehiclebased on a time of flight of communications between the mobilecommunication unit and one or more transceivers positioned in thevehicle. The base station may also be configured for determining alocation of the mobile communication unit relative to the vehicle basedon a time of flight of communications between the mobile communicationunit and three or more transceivers positioned in the vehicle. Stillfurther, the base station is configured for determining a location ofthe mobile communication unit relative to the vehicle based on a time offlight of communications between the mobile communication unit and fouror more transceivers positioned in the vehicle. Further yet, the basestation is configured for determining a location of the mobilecommunication unit relative to the vehicle based on a time of flight ofan ultra-wide band communications between the mobile communication unitand the at least one transceiver positioned in the vehicle.

In a further aspect, the mobile communication unit comprises a motionsensor configured to detect movements of the mobile communication unitand to communicate said movements to the base station. The determinationthat the mobile communication unit is substantially stationary relativeto the vehicle may be made in dependence on the detected movementscommunicated from the mobile communication unit to the base station.

In a further aspect, a method of facilitating control over a function ofa vehicle comprises providing a base station positioned in the vehicleand a mobile communication unit, the base station comprising a firsttransmitter and a first receiver. A signal is transmitted from the firsttransmitter to the mobile communication unit, and a signal is receivedfrom the mobile communication unit. The mobile communication unit iscaused to operate in accordance with a limited-response duty cycle. Alocation of the mobile communication unit may be determined relative tothe vehicle, and the mobile communication unit may be caused to operatein accordance with the limited-response duty cycle in response to adetermination that the mobile communication unit is located within thevehicle or in response to a determination that the mobile communicationunit is substantially stationary relative to the vehicle or further inresponse to a determination that the mobile communication unit islocated within the vehicle and that the mobile communication unit issubstantially stationary relative to the vehicle. The mobilecommunication unit may be caused to resume operating in accordance witha high-response duty cycle in response to an occurrence of apredetermined trigger event.

A method of facilitating control over a function of a vehicle mayfurther comprise determining a location of the mobile communication unitrelative to the vehicle based on a time of flight of communicationsbetween the mobile communication unit and one or more transceiverspositioned in the vehicle, based on a time of flight of communicationsbetween the mobile communication unit and three or more transceiverspositioned in the vehicle or based on a time of flight of communicationsbetween the mobile communication unit and four or more transceiverspositioned in the vehicle.

In another aspect, there is provided a vehicle having a communicationsystem as described in the foregoing aspects which may be adapted toperform a method as described in the preceding aspects.

Within the scope of this application it is expressly intended that thevarious aspects, embodiments, examples and alternatives set out in thepreceding paragraphs, in the claims and/or in the following descriptionand drawings, and in particular the individual features thereof, may betaken independently or in any combination. For example, featuresdescribed in connection with one embodiment are applicable to allembodiments unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described,by way of example only, with reference to the accompanying figures, inwhich:

FIG. 1 shows a schematic representation of a vehicle communicationsystem according to an embodiment of the present invention;

FIG. 2 shows the installation of the base station and transceivers ofthe vehicle communication system according to one embodiment of thepresent invention in a motor vehicle;

FIG. 3 shows an operating mode of the vehicle communication systemaccording to one embodiment of the present invention;

FIG. 4 illustrates another operating mode of the vehicle communicationsystem according to one embodiment of the present invention;

FIG. 5 illustrates another operating mode of the vehicle communicationsystem according to one embodiment of the present invention; and

FIG. 6 illustrates another operating mode of the vehicle communicationsystem according to one embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 shows a vehicle communication system 100 in accordance with anembodiment of the present invention. The vehicle communication system100 is configured to facilitate transfer of information among componentsof the vehicle communication system 100, which may further facilitatecontrol over one or more functions of a vehicle 102. Exemplary functionsthat may be controlled include, but are not limited to, enhanced PassiveEntry and Passive Start (ePEPS) keyless access, remote engine start,remote opening and closing of vehicle apertures, deployment andretraction of external mirrors or antennas, and/or activation anddeactivation of lighting and signalling systems of the vehicle 102.

The vehicle communication system 100 will be described with reference tothe vehicle 102 which has a front right door 142, a rear right door 144,a front left door 146 and a rear left door 148. The vehicle 102 also hasa boot lid 150 (also known as a deck lid) which can be locked/unlockedby the vehicle communication system 100 but this is not described hereinfor the sake of brevity. The doors 142-148 each have a lock mechanismand an external handle; and the front doors 142, 146 each have a foldingdoor mirror. The lock mechanisms each comprise a door lock switch toprovide a locking signal to indicate the status of the respective lockmechanism.

The vehicle communication system 100 comprises a base station 104 to beinstalled in the vehicle 102 to provide a Remote Function Actuator (RFA)for the vehicle 102. The base station 104 comprises an electroniccontrol unit 106, and a first rechargeable battery 108. The electroniccontrol unit 106 comprises a memory storage device 107 that is incommunication with one or more processor 109. The processor(s) 109 canbe configured to perform computational instructions stored in the memorystorage device 107. The first rechargeable battery 108 provides adedicated power supply for the base station 104 to enable its operationindependently from a vehicle power system (not shown).

The base station 104 further comprises first, second and thirdultra-wideband transceivers 110, 112, 114. The first transceiver 110 isprovided proximal the electronic control unit 106. The second and thirdtransceivers 112, 114 are positioned in the vehicle 102 remote from theelectronic control unit 106 and connected via a dedicated localinterconnect network (LIN) 116. The transceivers 110, 112, 114 each havean integrated antenna.

The base station 104 is connected to the vehicle systems (denotedgenerally by the reference numeral 118) via a CAN bus 120. The basestation 104 can thereby receive signals from the vehicle systems (e.g.,locking signals from door lock switches); and can control operation ofone or more vehicle systems (e.g., door lock mechanisms, closure systemsfor vehicle apertures such as windows, sun roof, ventilation systems,deck lid, engine start/ignition, vehicle lighting, entertainmentsystems, horn, heater, air conditioning, and the like). The CAN bus 120can also be employed to convey instructions from the electronic controlunit 106 to the engine control unit to enable/disable one or morevehicle systems (e.g., passive engine starting).

The vehicle communication system 100 further comprises a mobilecommunication unit 122 having a remote ultra-wideband transceiver 124and a second rechargeable battery 126. The mobile communication unit 122is portable to facilitate its being carried by the user. As describedherein, the mobile communication unit 122 communicates with the basestation 104 to facilitate control over vehicle functions, such aspassive entry to the vehicle 102, and, under some circumstances, toprovide information to a user in possession of the mobile communicationunit 122.

The base station 104 further comprises a dock 128 for receiving themobile communication unit 122. The dock 128 has a port 130 to enablecommunication between the base station 104 and the mobile communicationunit 122. A charging pad 132 is also provided in the dock 128 tofacilitate charging of the second rechargeable battery 126 when themobile communication unit 122 is docked and thus mated with the chargingpad 132. A bi-colour light emitting diode 134 is provided in the dock128 to indicate the status of the mobile communication unit 122 (forexample to indicate that the second rechargeable battery 126 is chargingor is fully charged). The charging pad 132 is connected to a powersupply unit (PSU) provided in the base station 104. An external chargeport 136 for the base station 104 is provided for charging the firstrechargeable battery 108.

The installation of the vehicle communication system 100 is illustratedin FIG. 2. The base station 104 and the first transceiver 110 arelocated at the rear of the vehicle 102 and the second and thirdtransceivers 112, 114 are located in the upper part of the vehicle 102(typically in the roof) on the right and left sides respectively of thevehicle 102. As illustrated by dashed lines in FIG. 2, the transceivers110, 112, 114 communicate with the mobile communication unit 122. Thedistance from each of the first, second and third transceivers 110, 112,114 to the remote transceiver 124 can be determined by measuringtransmission and/or response time (for example, time of flight for asignal transmission) thereby allowing the position of the mobilecommunication unit 122 in relation to the vehicle 102 to be determinedthrough triangulation. The use of ultra-wideband frequencies (typicallygreater than 3 GHz) allows the position of the mobile communication unit122 to be tracked with a relatively high degree of accuracy.

In accordance with such an embodiment of the vehicle communicationsystem 100, wherein the base station 104 comprises three transceivers110, 112, 114 disposed at spaced apart locations within the vehicle 102,it is possible to use the transmission and/or response times forcommunications sent between the mobile communication unit 122 and eachof the transceivers 110, 112, 114 to determine the position of themobile communication unit 122 relative to the vehicle 102 along each oftwo axes. For example, with the base station 104 and the firsttransceiver 110 located toward the rear of the vehicle 102 and thesecond and third transceivers 112, 114 disposed within the roof (onrespective left and right sides), the position of the mobilecommunication unit 122 in a horizontal plane around the vehicle 102 canreadily be determined, i.e. as shown in the plan view of FIGS. 2 to 6.

However, with the second and third transceivers 112, 114 disposed in thevehicle roof, and therefore lying in the same horizontal plane, theremay be situations in which it is not possible to readily determine theposition of the mobile communication unit 122 along a direction normalto the plan views of FIGS. 2 to 6. Accordingly, in a further embodimentof the invention, the vehicle communication system 100 may comprise afourth transceiver (not shown) which is disposed within the vehicle 102at a location which is spaced apart in a vertical direction from boththe plane of the vehicle roof and the horizontal plane in which the basestation 104 lies. For example, the fourth transceiver (not shown) couldbe mounted in the vehicle dashboard on the vehicle centre line. Withthis configuration, the height of the mobile communication unit 122relative to the vehicle 102 can readily be determined.

Thus, a position of the mobile communication unit 122 relative to thevehicle 102 may be periodically or continuously determined and may besaved in the memory storage device 107 for subsequent retrieval andanalyses by the processor 109. Such monitoring and storing andprocessing of position information may be useful for observing,tracking, and identifying certain rates, patterns, and/orcharacteristics of movement. For example, the vehicle communicationsystem 100 may be configured to detect the presence of the mobilecommunication unit 122 inside the passenger compartment of the vehicle102.

The remote transceiver 124 transmits a polling signal which, whenreceived by the first transceiver 110 of the base station 104, initiatescommunication between the base station 104 and the mobile communicationunit 122. In one embodiment, upon receipt of the polling signal, thefirst transceiver 110 responds by transmitting a challenge signal. Thechallenge signal is received by the mobile communication unit 122 andprompts the transmission of a response signal. The electronic controlunit 106 validates the response signal.

If the response signal is authenticated, the electronic control unit 106continues to communicate with the mobile communication unit 122 andtracks its position in relation to the vehicle 102 and may store theposition information in a the memory storage device 107 for retrievaland processing by the processor 109 in accordance with pre-definedinstructions.

Moreover, provided the challenge/response sequence is completedsuccessfully, the electronic control unit 106 will provide control overfunctions of the vehicle 102 subject to operating criteria beingsatisfied. If the response signal is not authenticated, the electroniccontrol unit 106 will not facilitate user control over vehiclefunctions, such as unlocking the doors of vehicle 102 or starting theengine of vehicle 102.

In one mode of operation, the polling signal is transmitted continuallyby the remote transceiver 124 so that communication with the basestation 104 is initiated by the mobile communication unit 122.Accordingly, the vehicle communication system 100 can initiate achallenge/response cycle without the need for user interaction, such asactuating a door handle.

In another mode of operation, such as may be active upon first entry ofthe vehicle 102 into service, to conserve energy stored in the secondrechargeable battery 126, the polling signal is transmitted for anoperating period of thirty (30) days. The transmission of the pollingsignal is stopped if the mobile communication unit 122 does notestablish communication with the base station 104 during the operatingperiod. A button provided on the mobile communication unit 122 can bepressed to re-commence transmission of the polling signal after saidoperating period has expired.

In another embodiment, the polling signal is transmitted intermittently,rather than continuously. In accordance with this embodiment, thepolling signal is repeated during the operating period with a timeinterval between transmission cycles (pulses), i.e. the polling signalis transmitted continually during the operating period. The timeinterval between the transmission cycles can be modified in response tomeasured parameters. For example, the time interval betweentransmissions can be modified depending on the measured distance betweenthe vehicle 102 and the mobile communication unit 122. If the mobilecommunication unit 122 is close to the vehicle 102, the time intervalcan be reduced to one (1) second. Conversely, if the mobilecommunication unit 122 is relatively far away from the vehicle 102, thetime interval can be increased to five (5) seconds, for example.

The base station 104 and the mobile communication unit 122 cancommunicate with each other over a range of at least 20 metres and anauthorization zone 138 having a radius of 2 metres is defined around thevehicle 102. When the electronic control unit 106 determines that themobile communication unit 122 is inside the authorization zone 138 itautomatically unlocks one or more of the vehicle's doors 142-49.Conversely, when the electronic control unit 106 determines that themobile communication unit 122 is outside the authorization zone 138, itautomatically locks the vehicle's doors 142-148.

As discussed above, a vehicle communication system 100 comprising threeor fewer transceivers may be able to determine a position of the mobilecommunication unit 122 relative to the vehicle 102 along only two axes.Accordingly, the authorization zone 138 may be defined in terms of onlythose two axes. A vehicle communication system 100 comprising four ormore transceivers, however, may be able to determine a position of themobile communication unit 122 relative to the vehicle 102 along anycombination of three (optionally orthogonal) axes. Accordingly, thelocation of the authorization zone 138 may be defined in terms positionsalong each the three axes, such that the authorization zone 138 (andthus the set of locations that are outside the authorization zone 138)may be defined in terms of three-dimensional space relative to thevehicle 102.

Being able to accurately determine the position of the mobilecommunication unit 122 in a three-dimension space around the vehicle 102may be particularly useful in certain situations, for example when thevehicle 102 is parked in a multi-level or multi-story car park oradjacent to a multi-story building. In such situations it is possiblethat the driver, having exited the vehicle 102 may move to another levelof the car park or building above or below the vehicle 102, but still beclose enough to the vehicle 102 to be within the authorization zone 138,resulting in one or more of the vehicle doors being unlocked.

Accordingly, if it is determined that the mobile communication unit 122is disposed sufficiently above or below the vehicle 102, such as in theexample of the multi-level car park, the electronic control unit 106 maynot unlock the vehicle doors even when the mobile communication unit 122would otherwise be judged to be within the authorization zone 138.

The electronic control unit 106 may be configured to operate the vehiclecommunication system 100 according to a number of operating modes. In anumber of scenarios, the mobile communication unit 122 is carried on theperson of the user and therefore follows the movements of the user.Movements of the user, and therefore, the mobile communication unit 122,are illustrated by a set of footprints 140. The process performed by thebase station 104 for authenticating the mobile communication unit 122 isthe same as described above and is common to each of the operatingmodes. In particular, the remote transceiver 124 transmits a pollingsignal which initiates an authentication cycle with the firsttransceiver 110. The base station 104 transmits a challenge signal whichtriggers transmission of a response signal from the mobile communicationunit 122. The electronic control unit 106 validates the response signaland, if successful, the base station 104 tracks the range and positionof the authenticated mobile communication unit 122. If theauthentication cycle is not successfully completed, for example due toan incorrect response signal being sent from the mobile communicationunit 122, the doors 142-148 will not be unlocked and the vehicle 102will not respond to the mobile communication unit 122.

The electronic control unit 106 may be configured to operate the vehiclecommunication system 100 according to a first operating mode asillustrated in FIG. 3. In this operating mode, the vehicle communicationsystem 100 operates to unlock the doors 142-148 on the side of thevehicle 102 on which the user approaches with the mobile communicationunit 122. Having authenticated the mobile communication unit 122 thebase station 104 tracks its range and position. In the illustratedexample, the electronic control unit 106 determines that the mobilecommunication unit 122 is on the right hand side of the vehicle 102.Once the base station 104 determines that the mobile communication unit122 is within the authorization zone 138, the electronic control unit106 automatically generates a door unlock signal to unlock both doors142, 144 on the right hand side of the vehicle 102. The door unlocksignal is transmitted via the CAN bus 120 and the front right door 142and the rear right door 144 are unlocked when the mobile communicationunit 122 enters the authorization zone 138. As the doors 142, 144 areunlocked before the user operates the respective door handle, in normaloperating conditions it is envisaged that there would be no perceptibledelay when the user operates the door handle.

In this mode, when the user operates the door handle on either the frontright door 142 or the rear right door 144, either a single-point entry(SPE) or a multiple-point entry (MPE) can be initiated. In single-pointentry mode, when the drivers door is the only opened door and the keyfob is taken into the vehicle, the rear door on the approached side willbe re-locked. For the avoidance of doubt, the drivers door does not haveto be closed to effect the locking of the rear door. If ANY door otherthan driver's door is opened, then all doors will be unlocked and remainso. The action of locking the rear door on the driver's side is causedby the key fob being detected inside the vehicle and thus no longer seenin the authorisation zone on the outside of the vehicle. In amultiple-point entry, the electronic control unit 106 generates controlsignals to unlock all of the other doors in the vehicle 102 when thedoor handle of either the front right door 142 or the rear right door144 is operated. It will be appreciated that the front left door 146 andthe rear left door 148 will be unlocked if base station 104 determinesthat the mobile communication unit 122 enters the authorization zone 138on the left hand side of the vehicle 102. Only when the door handle ofone of the unlocked doors 142-148 is operated is an indication providedthat the doors have been unlocked, for example by flashing the siderepeaters and/or extending the door mirrors. If none of the door handlesare operated, no indication is provided that one or more of the doors142-148 have been unlocked.

The electronic control unit 106 may be configured to operate the vehiclecommunication system 100 according to a second operating mode asillustrated in FIG. 4 to accommodate a walk-past scenario. In thiswalk-past scenario, the user enters and exits the authorization zone 138but does not operate a door handle. As in the first mode describedabove, the base station 104 authenticates the mobile communication unit122 as it approaches the vehicle 102. In this case, the base station 104tracks the position of the mobile communication unit 122 and determinesthat the user is approaching from the rear of the vehicle 102 on theright hand side. As described above in regard to the first mode ofoperation, when the vehicle communication system 100 detects that themobile communication unit 122 has entered the authorization zone 138, asit has in this walk-past scenario, a door unlock signal is transmittedto unlock the front right door 142 and the rear right door 144.

In this scenario, however, the user does not operate the door handle oneither of the doors 142, 144 and, instead, walks past the vehicle 102.Since the vehicle communication system 100 is tracking the position ofthe mobile communication unit 122, the vehicle communication system 100is able to determine when the mobile communication unit 122 leaves theauthorization zone 138. Accordingly, upon the departure of the mobilecommunication unit 122 from the authorization zone 138, and lacking thereceipt of any indication that a door handle has been operated, the basestation 104 transmits a door lock signal to lock the front right door142 and the rear right hand door 144 or otherwise facilitates there-locking of those doors. In one embodiment, the vehicle 102 does notprovide a visual indication when the doors 142, 144 are unlocked orsubsequently locked.

The electronic control unit 106 may be configured to operate the vehiclecommunication system 100 according to a third operating mode asillustrated in FIG. 5 to facilitate the automatic locking of the doors142-148 when the user walks away from the vehicle 102. In this scenario,the user exits the vehicle 102 carrying the mobile communication unit122 and closes the vehicle doors 142-148. In the illustrated example,the user exits the vehicle 102 through the front right door 142 and thencloses it. The user then walks away from the vehicle 102 carrying themobile communication unit 122. As the mobile communication unit 122 iscarried away from the vehicle 102, the vehicle communication system 100tracks the location of the mobile communication unit 122 and comparesthat location to the definition of the authorization zone 138. If andwhen the vehicle communication system 100 determines that the mobilecommunication unit 122 has left the authorization zone 138, the vehiclecommunication system 100 transmits a door lock signal to lock the doors142-148. The vehicle 102 is thereby secured automatically without theuser activating the mobile communication unit 122 or taking any actionother than walking away from the vehicle 102. A security protocol tocomply with industry standards, for example those specified byThatcham®, would typically be undertaken for the automatic locking ofthe doors 142-148. Under normal operating conditions, the automaticlocking of the vehicle 102 does not double-lock the vehicle 102. Rather,the vehicle 102 would only be double-locked if the user specificallyselected this locking mode, for example via a control panel in thevehicle 102.

The electronic control unit 106 may be further configured to operate thevehicle communication system 100 according to a fourth operating mode asillustrated in FIG. 6 to accommodate a mis-lock scenario. This mode issimilar to the third operating mode described above insofar as the userexits the vehicle 102 through the front right door 142 and closes thedoor 142 before walking away from the vehicle 102. In connection withthis fourth operating mode, the vehicle communication system 100 againdetermines if and when the mobile communication unit 122 has departedthe authorization zone 138. As illustrated in FIG. 6, however, the rearleft door 148 is ajar, and the electronic control unit 106 determinesthat the door 148 cannot be locked (a so-called mis-lock).

To avoid the user leaving the vehicle 102 in an unsecure state (as mayotherwise occur if the operator had not noticed that the rear left door148 was ajar) the electronic control unit 106 transmits an alert signalto the CAN bus 120 and a notification is provided to the user. Forexample, the CAN bus 120 may illuminate the side repeaters and/orprovide an audible warning to notify the user that the doors 142-148have not all been locked. When the rear left door 148 is closed, thevehicle communication system 100 will lock the door 148 to secure thevehicle 102.

In conjunction with the above-described modes of operation, theelectronic control unit 106 may be configured to operate the vehiclecommunication system 100 according to a fifth operating mode,accommodating an in-vehicle scenario. In order to conserve energy storedin the second rechargeable battery 126 of the mobile communication unit122, it may be desirable, in certain situations, for one or morecomponents of the vehicle communication system 100, such as the mobilecommunication unit 122, to operate in a modified, energy-conservingmanner. For example, when the mobile communication unit 122 has remainedsubstantially stationary relative to the vehicle 102 for greater than apredetermined period of time, and remains in a location within thevehicle 102, it may be determined that the likelihood of an immediateand urgent need for two-way communication involving the mobilecommunication unit 122 may be relatively low. Accordingly, the basestation 104 may instruct the mobile communication unit 122 to enter adriving mode.

In such a driving mode, in response to a command received from the basestation 104, the transceiver 124 of the mobile communication unit 122 iscaused to perform according to a modified, limited-response duty cycle.While the vehicle communication system 100 is operating in a mode thatrequires relatively immediate response from the mobile communicationunit 122, the transceiver 124 of the mobile communication unit 122operates according to a high-response duty cycle such that thetransceiver 124 remains substantially active at all times, withrelatively little or no periods of inactivity. Accordingly, relativelylittle time lag exists between a transmission of a command signal fromthe first transceiver 110 and a transmission of a response from themobile communication unit 122. When the mobile communication unit 122performs according to the modified, limited-response, duty cycle,however, the transceiver 124 of the mobile communication unit 122remains substantially inactive for the majority of each cycle, withrelatively little time of activity within each cycle. Therefore, arelatively greater time lag exists between transmission of a commandsignal from the first transceiver 110 and the transmission of a responsefrom the mobile communication unit 122.

Accordingly, a high-response duty cycle comprises an active phase thatoccurs without substantial interruption by an inactive phase. Alimited-response duty cycle comprises active phases that are interruptedby periods on inactivity. In one such embodiment, a period of inactivitymay extend for approximately two seconds, during which time thetransceiver 124 is in an inactive state and therefore unable to receivea transmission, such as a command signal transmitted by the base station104. In each active phase occurring between the periods of inactivity,the transceiver 124 of the mobile communication unit 122 is activatedfor a few microseconds (e.g., between approximately one microsecond andapproximately ten microseconds, for approximately three microseconds).During these intervening active periods, the transceiver 124 is capableof receiving transmissions, including command, polling or challengesignals or other information transmitted by the base station 104. Duringextended time periods of driving, the mobile communication unit 122performs this modified, limited-response, duty cycle, continuouslyalternating between the longer periods of deactivation and therelatively brief periods of activation. Thus, in accordance with thismodified duty cycle, energy consumption by the mobile communication unit122 may be substantially reduced.

In the event that it becomes necessary or useful to resume two-waycommunications between the base station 104 and the mobile communicationunit 122, the base station 104 transmits a continuous wake-uptransmission pulse lasting for at least as long as the length of eachperiod of deactivation. Accordingly, as soon as the mobile communicationunit 122 enters an active phase in its duty cycle, the mobilecommunication unit 122 encounters the wake-up transmission pulse. Uponreceiving the wake-up transmission pulse, the mobiletransmitter-receiver would take the appropriate action depending on whatthe base station 104 commands the mobile communication unit 122 to do.

A number of scenarios may arise wherein it may be desirable for the basestation 104 to resume communications with the 122 during the drivingmode. For example, whenever a door is opened and closed, it may benecessary to perform a search for the presence of a mobile communicationunit 122 within the passenger compartment of the vehicle 102. If thereis no mobile communication unit 122 present, the base station 104 mayalert the driver and/or disable certain features and functions of thevehicle, in particular to disable the engine or immobilise the vehicle.To facilitate the search, a wake-up command is issued by the basestation 104 whenever a door is opened. Thus, the vehicle communicationsystem 100 provides an energy-saving in-vehicle mode withoutcompromising relatively continuous communication between the basestation 104 and the mobile communication unit 122.

The vehicle communication system 100 can optionally also provide keylessengine starting for the vehicle 102. By using the ranging data from thetransceivers 110, 112, 114, the electronic control unit 106 candetermine when the mobile communication unit 122 is inside the vehicle102. A control signal can be transmitted to the engine control unit, viathe CAN bus 120, to permit keyless engine starting when a Start buttonis pressed.

The vehicle communication system 100 according to the present inventioncan be further refined. In particular, the electronic control unit 106can be configured to transmit a status signal to the mobilecommunication unit 122. For example, if the base station 104 detects amis-lock scenario, the status signal may instruct the mobilecommunication unit 122 to generate a first user alert. Equally, thestatus signal may instruct the mobile communication unit 122 to generatea second user alert (which is different from the first user alert) whenthe vehicle 102 has been locked. The first and/or the second user alertcould be provided instead of, or in addition to, any notificationprovided by the vehicle 102. The mobile communication unit 122 couldcomprise an audio, optical or haptic output for indicating the vehiclestatus. For example, the mobile communication unit 122 could compriseone or more of the following: LED(s), a text screen or a vibratingmechanism.

The mobile communication unit 122 is also provided with one or morebuttons to allow a user to trigger locking/unlocking of the vehicledoors from outside of the authorization zone 138.

The ultra-wideband (UWB) transceivers 110, 112, 114, 124 describedherein are compliant with IEEE802.15.4a protocol.

The vehicle communication system 100 can monitor time of flight (ToF)communications between the base station 104 and the mobile communicationunit 122 to provide improved security, for example to protect against arelay-station security attack.

A door unlock override switch can be provided to unlock the doors142-148 in the event of an emergency.

The skilled person will understand that various changes andmodifications can be made to the vehicle communication system 100described herein without departing from the spirit and scope of thepresent invention. For example, a welcome lights function could besupported by illuminating an interior and/or exterior vehicle light whenthe mobile communication unit 122 enters the authorization zone 138.

Although the vehicle communication system 100 has been described withreference to the mobile communication unit 122 transmitting the pollingsignal, the system could also operate if the base station 104transmitted the polling signal. For example, the first transceiver 110of the base station 104 may transmit a polling signal which, whenreceived by the remote transceiver 124, initiates communication betweenthe mobile communication unit 122 and the base station 104. In oneembodiment, upon receipt of the polling signal, the mobile communicationunit responds by transmitting a response signal. The response signal isreceived by the first transceiver 110, and the electronic control unit106 validates the response signal.

The mobile communication unit 122 may include a motion sensor 152, suchas a gyroscope or an accelerometer, to detect movements of the mobilecommunication unit 122. Signals based on the detected movements may thenbe transmitted to the base station 104 for use in deciding whether, whenand how to facilitate control over vehicle functions. For example, ifthe base station 104 determines that the mobile communication unit 122has been stationary for a predetermined period of time, the base station104 may cause the mobile communication unit 122 to be disabled or toenter a sleep mode. Alternatively, when the vehicle communication systemis operating according to the aforementioned fifth operating mode andthe mobile communication unit 122 has remained substantially stationaryrelative to the vehicle 102 for greater than a predetermined period in alocation within the vehicle, the base station 104 shall instruct themobile communication unit 122 to enter the driving mode. In addition,the base station 104 could transmit a disable signal to deactivate thetransceivers 110, 112, 114, 124. Alternatively, the transceivers 110,112, 114, 124 could be disabled automatically if they do not receive anauthorization signal for a predetermined period of time. The mobilecommunication unit 122 could be awakened by an activation signal fromthe motion sensor 152 when it detects movement.

Moreover, it will be appreciated that it is not necessary for a vehiclecommunication system 100 according to the present invention to provideall of the operating modes described herein. Rather, one or more of theoperating modes could be embodied in a communication system inaccordance with the present invention.

It will be appreciated that various changes and modifications can bemade to the present invention without departing from the presentinvention. Further aspects of the present invention will be understoodwith reference to the following numbered paragraphs.

1. A communication system for facilitating control over a function of avehicle (102), the communication system comprising:

a base station (104) positioned in the vehicle (102); and a mobilecommunication unit (122);

the base station (104) comprising a first transmitter for transmitting asignal to the mobile communication unit (122) and a first receiver forreceiving a signal from the mobile communication unit (122);

the base station (104) being further configured to cause the mobilecommunication unit (122) to operate in accordance with alimited-response duty cycle.

2. A communication system as described in paragraph 1, wherein the basestation (104) is configured for determining a location of the mobilecommunication unit (122) relative to the vehicle (102).

3. A communication system as described in paragraph 1 or 2, wherein thebase station (104) is configured to cause the mobile communication unit(122) to operate in accordance with the limited-response duty cycle inresponse to a determination that the mobile communication unit (122) islocated within the vehicle (102).

4. A communication system as described in paragraph 2, wherein the basestation (104) is configured to cause the mobile communication unit (122)to operate in accordance with the limited-response duty cycle inresponse to a determination that the mobile communication unit (122) issubstantially stationary relative to the vehicle (102).

5. A communication system as described in paragraph 2, wherein the basestation (104) is configured to cause the mobile communication unit (122)to operate in accordance with the limited-response duty cycle inresponse to a determination that the mobile communication unit (122) islocated within the vehicle (102) and the mobile communication unit (122)is substantially stationary relative to the vehicle (102).

6. A communication system as described in paragraph 2, wherein the basestation (104) is configured to cause the mobile communication unit (122)to resume operating in accordance with a high-response duty cycle inresponse to an occurrence of a predetermined trigger event.

7. A communication system as described in paragraph 6, wherein thepredetermined trigger event is based at least in part upon an opening ofa door (142) of the vehicle (102).

8. A communication system as in paragraph 6, wherein the predeterminedtrigger event is based at least in part upon a closing of a door (142)of the vehicle (102).

9. A communication system as in paragraph 6, wherein the predeterminedtrigger event is based at least in part upon a request to start anengine of the vehicle (102).

10. A communication system as described in paragraph 1, wherein thelimited-response duty cycle comprises a period of inactivity, duringwhich the mobile communication unit (122) is unable to receive atransmission, and a period of activity, during which the mobilecommunication unit (122) is capable of receiving a transmission.

11. A communication system as described in paragraph 10, wherein theperiod of inactivity is longer in time than a period of activity.

12. A communication system as described in paragraph 10, wherein aperiod of inactivity extends for approximately two seconds before asubsequent period of activity.

13. A communication system as described in paragraph 10, wherein aperiod of activity extends for approximately three microseconds before asubsequent period of inactivity.

14. A communication system as described in paragraph 6, wherein thehigh-response duty cycle comprises a period of activity, during whichthe mobile communication unit (122) is capable of receiving atransmission.

15. A communication system as described in paragraph 14, wherein theperiod of activity occurs without substantial interruption by a periodof inactivity.

16. A communication system as described in paragraph 15, wherein theperiod of inactivity is not longer in duration than one second.

17. A communication system as described in paragraph 15, wherein theperiod of inactivity is not longer in duration than one half of onesecond.

18. A communication system as described in paragraph 2, wherein the basestation (104) is configured for determining a location of the mobilecommunication unit (122) relative to the vehicle (102) based on a timeof flight of communications between the mobile communication unit (122)and one or more transceivers (110) positioned in the vehicle (102)

19. A communication system as described in paragraph 18, wherein thebase station (104) is configured for determining a location of themobile communication unit (122) relative to the vehicle (102) based on atime of flight of communications between the mobile communication unit(122) and three or more transceivers (110) positioned in the vehicle(102).

20. A communication system as described in paragraph 19, wherein thebase station (104) is configured for determining a location of themobile communication unit (122) relative to the vehicle (102) based on atime of flight of communications between the mobile communication unit(122) and four or more transceivers (110) positioned in the vehicle(102).

21. A communication system as described in paragraph 18 wherein the basestation (104) is configured for determining a location of the mobilecommunication unit (122) relative to the vehicle (102) based on a timeof flight of an ultra-wide band communications between the mobilecommunication unit (122) and the at least one transceiver (124)positioned in the vehicle (102).

22. A communication system as described in paragraph 1, the mobilecommunication unit (122) comprising a motion sensor (152) configured todetect movements of the mobile communication unit (122) and tocommunicate said movements to the base station (104).

23. A communication system as described in paragraph 22 when directly orindirectly dependent on claim 4 wherein the determination that themobile communication unit (122) is substantially stationary relative tothe vehicle (102) is made in dependence on the detected movementscommunicated from the mobile communication unit (122) to the basestation (104).

24. A method of facilitating control over a function of a vehicle (102)comprising:

providing a base station (104) positioned in the vehicle (102) and amobile communication unit (122), the base station (104) comprising afirst transmitter and a first receiver;

transmitting a signal from the first transmitter to the mobilecommunication unit (122);

receiving a signal from the mobile communication unit (122); and causingthe mobile communication unit (122) to operate in accordance with alimited-response duty cycle.

25. A method of facilitating control over a function of a vehicle (102)as described in paragraph 24, further comprising determining a locationof the mobile communication unit (122) relative to the vehicle (102).

26. A method of facilitating control over a function of a vehicle (102)as described in paragraph 25, further comprising causing the mobilecommunication unit (122) to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit (122) is located within the vehicle (102).

27. A method of facilitating control over a function of a vehicle (102)as described in paragraph 25, further comprising causing the mobilecommunication unit (122) to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit (122) is substantially stationary relative tothe vehicle (102).

28. A method of facilitating control over a function of a vehicle (102)as described in paragraph 25, further comprising causing the mobilecommunication unit (122) to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit (122) is located within the vehicle (102) andthe mobile communication unit (122) is substantially stationary relativeto the vehicle (102).

29. A method of facilitating control over a function of a vehicle (102)as described in paragraph 25, further comprising causing the mobilecommunication unit (122) to resume operating in accordance with ahigh-response duty cycle in response to an occurrence of a predeterminedtrigger event.

30. A method of facilitating control over a function of a vehicle (102)as described in paragraph 24, further comprising determining a locationof the mobile communication unit (122) relative to the vehicle (102)based on a time of flight of communications between the mobilecommunication unit (122) and one or more transceivers (110) positionedin the vehicle (102).

31. A method of facilitating control over a function of a vehicle (102)as described in paragraph 24, further comprising determining a locationof the mobile communication unit (122) relative to the vehicle (102)based on a time of flight of communications between the mobilecommunication unit (122) and three or more transceivers (110) positionedin the vehicle (102).

32. A method of facilitating control over a function of a vehicle (102)as described in paragraph 24, further comprising determining a locationof the mobile communication unit (122) relative to the vehicle (102)based on a time of flight of communications between the mobilecommunication unit (122) and four or more transceivers (110) positionedin the vehicle (102).

33. A vehicle (102) having a communication system, or being adapted toperform a method as described in paragraph 1 or 24.

Unless precluded by incompatibility, each of the claims set out belowmay be dependent on any preceding claim.

1. A communication system for facilitating control over a function of avehicle, the communication system comprising: a base station positionedin the vehicle; and a mobile communication unit; the base stationcomprising a first transmitter for transmitting a signal to the mobilecommunication unit and a first receiver for receiving a signal from themobile communication unit; the base station being further configured tocause the mobile communication unit to operate in accordance with alimited-response duty cycle, wherein the base station is configured tocause the mobile communication unit to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit is located within the vehicle.
 2. Thecommunication system of claim 1, wherein the base station is configuredfor determining a location of the mobile communication unit relative tothe vehicle. 3-4. (canceled)
 5. The communication system of claim 1,wherein the base station is configured to cause the mobile communicationunit to operate in accordance with the limited-response duty cycle inresponse to a determination that the mobile communication unit islocated within the vehicle and the mobile communication unit issubstantially stationary relative to the vehicle.
 6. The communicationsystem of claim 1, wherein the base station is configured to cause themobile communication unit to resume operating in accordance with ahigh-response duty cycle in response to an occurrence of a predeterminedtrigger event.
 7. The communication system of claim 6, wherein thepredetermined trigger event is based at least in part upon one or moreof an opening of a door of the vehicle, a closing of a door of thevehicle, and/or a request to start an engine of the vehicle. 8-9.(canceled)
 10. The communication system of claim 1, wherein thelimited-response duty cycle comprises a period of inactivity, duringwhich the mobile communication unit is unable to receive a transmission,and a period of activity, during which the mobile communication unit iscapable of receiving a transmission, and wherein the period ofinactivity is longer in time than the period of activity. 11-13.(canceled)
 14. The communication system of claim 6, wherein thehigh-response duty cycle comprises a period of activity, during whichthe mobile communication unit is capable of receiving a transmission,and wherein the period of activity occurs without substantialinterruption by a period of inactivity. 15-17. (canceled)
 18. Thecommunication system of claim 1, wherein the base station is configuredfor determining a location of the mobile communication unit relative tothe vehicle based on a time of flight of communications between themobile communication unit and one or more transceivers positioned in thevehicle.
 19. The communication system of claim 1, wherein the basestation is configured for determining a location of the mobilecommunication unit relative to the vehicle based on a time of flight ofcommunications between the mobile communication unit and three or moretransceivers positioned in the vehicle.
 20. The communication system ofclaim 1, wherein the base station is configured for determining alocation of the mobile communication unit relative to the vehicle basedon a time of flight of communications between the mobile communicationunit and four or more transceivers positioned in the vehicle.
 21. Thecommunication system of claim 18, wherein the base station is configuredfor determining a location of the mobile communication unit relative tothe vehicle based on a time of flight of ultra-wide band communicationsbetween the mobile communication unit and the one or more transceiverspositioned in the vehicle.
 22. The communication system of claim 1,wherein the mobile communication unit comprises a motion sensorconfigured to detect movement of the mobile communication unit and tocommunicate the movement to the base station.
 23. The communicationsystem of claim 5, wherein the determination that the mobilecommunication unit is substantially stationary relative to the vehicleis made in dependence on a detected movement communicated from themobile communication unit to the base station.
 24. A method offacilitating control over a function of a vehicle, the methodcomprising: providing a base station positioned in the vehicle and amobile communication unit, the base station comprising a firsttransmitter and a first receiver; transmitting a signal from the firsttransmitter to the mobile communication unit; receiving a signal fromthe mobile communication unit; and causing the mobile communication unitto operate in accordance with a limited-response duty cycle in responseto a determination that the mobile communication unit is located withinthe vehicle.
 25. The method of claim 24, further comprising determininga location of the mobile communication unit relative to the vehicle.26-27. (canceled)
 28. The method of claim 25, further comprising causingthe mobile communication unit to operate in accordance with thelimited-response duty cycle in response to a determination that themobile communication unit is located within the vehicle and the mobilecommunication unit is substantially stationary relative to the vehicle.29. The method of claim 25, further comprising causing the mobilecommunication unit to resume operating in accordance with ahigh-response duty cycle in response to an occurrence of a predeterminedtrigger event.
 30. The method of claim 24, further comprisingdetermining a location of the mobile communication unit relative to thevehicle based on a time of flight of communications between the mobilecommunication unit and one or more transceivers positioned in thevehicle. 31-32. (canceled)
 33. A vehicle comprising the communicationsystem of claim
 1. 34. A vehicle configured to perform the method ofclaim 24.